Hydraulic hose specification/replacement

[Jim Edwards]

Hi,  I needed to replace a Hydraulic hose running from my Sauer Danfoss hyd pump to the side radiator fan motor. The hose had been chafing against the air intake pipe as well as the frame and had gone through the outer layer of the hose starting to fray the steel braiding in those to locations. I cannot identify the hose / rating of the existing hose. It is a gates something but none numbers turn up on a internet search. The service center that did the work used a 3100 psi msha ic-227/9 fras & abrasion resistant hose from RYCO. The Hyd pump that drives this is a Sauer Danfoss CPC-10?? ( of course label is damaged and can't read the last 2 numbers and build sheet has incorrect lists date code as model number) so I cant look up the output of the pump. The guys that did the work are nice guys but that doesn't always translate to being competent. I just keep thinking of Johnny and Richard in that this hose is on the hot side of the motor.

So the question; Is the (a) 3100 psi hose adequate for this application?
The moral is check your hoses!

thanks

[Mike Shumack]

The Danfoss pump specs say pump pressure can reach 4000 psi peak (depending the specific pump), and Beaver manual says typical hyd system pressure is around 2,000 psi.
My DanFoss pump is a "CPC-1018".

So I personally would go with a hose rated for 4,000 psi.  But a 3,000 psi rated hose is probably good enough.
When I get home, I'll see if I can identify the hyd hose used on my coach.


Update: I've attached a picture of the hydraulic hose used for my rear hyd lift (it's rated for 5,800 psi working pressure). I could not get under the coach just now to see if there are any useful markings on the hose for fan/steering.

[Dave Atherton]

Gentleman, I would recommend going to 4 ply hydraulic hose rated at 4000 psi with a burst or spike pressure rated at 6700 psi. 2 ply hydraulic hoses have a working pressure 2000 psi and burst or spike pressure 2550 psi. Most all 2 ply hydraulic hoses can be made up at local parts stores. A 4 ply hydraulic hose has to be made up at a hydraulic shop.  I have a hydraulic hose machine and only make up 4 ply hoses because many people do not understand burst pressure. A lot of damage has happened over the years due to under-rated hoses.  Dave Atherton Retired Cat Mechanic

[Jim Edwards]

Hi Dave. I found the specs on the hose and it has a continuous working pressure of 3,100 psi and a minimum burst pressure of 12,400 psi. So I am thinking I am OK.

[Dave Atherton]

Jim,
That is a good hose for the pump output. The mfg has built the hose with  the intended use and the high burst pressure as safety feature in mind. This brings up a few suggestions to consider when replacing hydraulic hoses. Leveling jacks,  slideout, and steering are considered low pressure hydraulics and a 2 ply hydraulic hose can be made up in most cases at local parts houses like Napa Auto Parts etc. Be sure to get the same size or larger diameter hose. Do not get a smaller diameter hose with same size fittings. Be sure the hydraulic pressure hose crimped fittings have the same I.D. as hose being made (if not it will change the value of fluid flow and pressure). Lastly, always check that the return hose to hydraulic tank is the same size or larger to maintain the correct pressure in the hydraulic system. Mismatching the pressure and return hose can result in back pressure on the return side of the hydraulic pump, creating heat within the system. Actual pressure cannot exceed 25% above normal system pressure. This commonly is seen in hydraulic fan motors due to mismatched replacement hoses.
Dave Atherton Retired Cat Mechanic